OLIMEX© 2015
A20-SOM user's manual
1.4 Board variants
There are two major board variants named: A20-SOM and A20-SOM-4GB. The 4GB version has
built-in NAND memory that allows the storage of an operating system without the need of a SD
card (at the moment of writing this document Olimex provides only Android OS for the NAND).
The 4GB version comes with already programmed and ready-to-use Android OS image.
The other Olimex board with close characteristics is A13-SOM board. It is much cheaper and
smaller. It heats less and consumes less power. However, it features a generation older processor
and lesser amount of RAM memory, making it less desirable for heavy computations (for instance,
high resolution video decoding and encoding).
Other SOM boards that might be compared to functionality are the and quad-core ARM Cortex-A9
RK3188-SOM and the BeagleBone-inspired AM3352-SOM.
1.5 Board versions used in the manual
The documents follows the hardware layout of A20-SOM board revision D. There might be revision
B pictures left over.
Note that major changes in the hardware design were introduced in A20-SOM board revision C.
Boards from the initial couple of revisions have visible differences compared to boards from
revisions C and on. Yet, the two major functional differences are the improved memory clock speed
(480MHz compared to the initial 384MHz) and the presence of the additional GPIO-6 connector. It
is important to notice that different board revision might use different Debian images!
A20-SOM-EVB revision C peripheral board was used while writing this document.
Different board revisions might have different features or settings. It is possible that parts of this
document do not apply to all board revisions.
1.6 Document organization
Each section in this document covers a separate topic, organized as follows:
–
Chapter 1 is an overview of the board usage and features
–
Chapter 2 provides a guide for quickly setting up the board and software notes
–
Chapter 3 contains the general board diagram and layout
–
Chapter 4 describes the component that is the heart of the board: the A20 – Allwinner
processor
–
Chapter 5 is an explanation of the control circuitry associated with the microcontroller
–
Chapter 6 covers the connector pinout, peripherals and jumper description
–
Chapter 7 provides the schematics and the dimensions of the board
–
Chapter 8 contains the revision history, useful links and support information
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